With apologies to Ron Popeil, we have a link resolver setup which has served us well over the years. Once the initial configuration and setup w/ e-resource vendors was complete, we only change one configuration setting (on a server we manage) to change link resolvers.

We point all of our e-resource vendors to a locally hosted domain whose job is to re-write the locally-defined openURL to the current one.

Many years ago we registered this base URL with all our providers:

http://resolver.lib.washington.edu/resserv?

resolver.lib has a RewriteRule that rewrites the incoming query with the current base URL (currently http://alliance-primo.hosted.exlibri...?{queryString} for Alma) and then sends it on it's way.

So when we change resolvers, the only change that needs to happen is in the rewrite rule itself. With this approach, it was (thankfully!) very easy for us to change from our old resolver to Alma.